ADA: Insulin Pump Suspend Feature Halts Hypoglycemia

Action Points

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Explain that insulin pumps that automatically shut down when blood glucose hits a certain low level decrease the amount of time pediatric patients spend in hypoglycemia.

Note that there were no differences in mean glucose concentrations, glycemic variability, or time spent in the high glucose region with and without the low glucose suspend technology activated.

SAN DIEGO -- Insulin pumps that automatically shut down when blood glucose hits a certain low level decrease the amount of time pediatric patients spend in hypoglycemia, researchers said here.

Sensor-augmented pump therapy with a low glucose suspend mechanism, which shuts the device off when blood sugar levels dip below 70 mg/dL, halved the time patients were hypoglycemic, Thomas Danne, MD, of Hanover Medical School in Germany, and colleagues reported at a scientific session at the American Diabetes Association meeting here.

"It does work, and it significantly reduces rates of hypoglycemia," Danne said, adding that he believes the technology "is ready for prime-time."

Low glucose suspend technology sounds an alarm when patients appear to be descending into low blood sugar. Patients can respond and turn the alarm off; if they don't, the pump will shut down for two hours, Danne explained, then resume infusion for another four hours.

In some cases, after or during that time, patients may have another two-hour cycle of suspension, Danne said.

Low glucose suspend is an early incarnation of the artificial pancreas, according to Chip Zimliki, PhD, chair of the FDA's critical path initiative on the closed-loop device. It's used with sensor-augmented pump therapy, which lacks a control algorithm -- the hallmark of the artificial pancreas system -- that automatically deploys or withholds insulin on an as-needed basis.

Thus, the patient still controls the insulin dose. Still, having an automatic shut off could potentially be incorporated into a closed-loop system.

The FDA recently released a draft guidance on low glucose suspend technology, which will be followed up by a guidance on two other incarnations of the artificial pancreas: control-to-range and control-to-target, Zimliki said.

The goal is to establish unified targets for bringing these devices to market faster, he said.

For their study, Danne and colleagues enrolled 24 patients with type 1 diabetes, whose median age was 10.8 years. Patients were given two weeks of pump training, followed by five weeks of use of the pump with the low glucose suspend function turned on.

Danne said there were more alerts during the day than during the night (76% versus 24%), but there were more shutdowns overnight (84% versus 16%) and that's because patients turn off the devices when the alarm sounds and manage their condition.

"As you may imagine, the patient responds and it's not likely that you'll have the 120-minute suspension during the daytime," Danne said.

When the device did shut down, glucose levels did become elevated, rising a mean of 68.4 mg/dL or about 35 mg/dL per hour.

There were no differences in mean glucose concentrations, glycemic variability, or time spent in the high glucose region with and without the low glucose suspend technology activated.

"There's no risk that you'll lose your good glycemic control by having the low glucose suspend," Danne said.

But they did find significant differences in hypoglycemic excursions and time spent in the low glucose region. Time in hypoglycemia fell 50% (P=0.002), Danne said.

There were also fewer glucose values below 40 mg/dL when the low glucose suspend technology was turned on.

Danne added that there were no cases of diabetic ketoacidosis, and the device received good rates of patient-reported satisfaction.

William Tamborlane, MD, of Yale School of Medicine in New Haven, Conn., who moderated the session during which the findings were presented, said suspending only when patients reach 70 mg/dL will still lead to hypoglycemic excursions, largely because of a well-known caveat that interstitial sampling doesn't necessarily concur with serum glucose levels.

On the other hand, Robert Henry, MD, chief of medicine and science for the ADA, said the 70 mg/dL level is close to the right range, but varies depending on the patient. Even non-diabetic patients can have excursions below that level and be fine, so it may end up being over-responsive, he said.

Tamborlane also pointed out that a closed-loop system would also be able to prevent hyperglycemia, especially during exercise when kids tend to turn their pumps off.

During that time, Tamborlane noted, patients can consume a sports drink or other carbohydrate-filled drinks.

Tamborlane pointed out that a device that automatically kicks back into action when needed would be a great benefit. "Having a system that can kick in and also prevent high blood glucose might be a more rational approach than hoping the system will just shut down," he said.

The study was supported by Medtronic. The company's Paradigm VEO system was used in this study.

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